Off-peak water heating system



H. M. BIEBEL Filed Oct. 17, 1940 INV E NTO R 7 /'7f HEHMA/VMB/EBEL ATTO R N EY OFF-PEAK WATER HEATING SYSTEM Dec. 16,A 1941.

'Patented Dec. ,16,v 1941 2,266,146 oFF-PEAK WATER. HEATING SYSTEM Herman M. Biebel, Elgin, Ill., assignor to McGraw' Electric Company, Elgin, Ill., a corporation of Delaware Application October 17, 1940, Serial N0. 361,510 8 Claims. (Cl. 21S- 39) My invention relates to hot water tanks and particularly to orf-peak water heating systems to be used with domestic hot water tanks.

One of the objects of my invention is to provide a relatively simple water heating system embodying a minimum number of elements whereby to control the energization of a hot water tank heating element. y

Another object of my invention is to provide an off -peak water heating system, controlled primarily by a constantly operating clock or timing means which will ensure heating of at least the major portion of the water in a tank during the oif -peak period.

Another object of my invention is to provide an off-peak water heating system embodying means for delaying energization of the heater if the tank contains more than a predetermined amount of hot water at the start of an off-peak period and Awhich includes also means ensuring the continuation of energization of the electric heating element after the end of an off-peak period if the tank contains an appreciable amount of -cold water at the end of an off-peak period.

Other objects of my invention will either be apparent from a description of one form of system embodying my invention or willbepointed out in the course of such description and will be particularly set forth in the appended claims. In the single sheet of drawing: Figure 1 is a view showing schematically my improved system applied to an ordinary domestic hot water tank, the latter being shown in vertical section, and,

Fig. 2 is a fragmentary view showing more particularly the control elements in a different position than that in which they are shown in Fig. 1 of the drawing.

I have illustrated a hot water tank ll of the elongated cylindrical type usually used in domestic installations, this tank -being provided with a bottom inlet pipe I3 for cold water and a top outlet pipe I5 for hot water. The tank may be surrounded with heat insulating materialA I1 and this may be encased in an .outer sheet metal casing I9, al1 of these elements being old in the art and constituting no part of my invention. While I have illustrated specific forms of tank elements, my invention is not to be considered as being limitedto the form shown in the drawing.

I provide also a continuously operative timing means designated in its entirety by the numeral 2l this including an electric motor 23 of the kind now used on electric circuits for operating timers. k'I'his motor is energized by being continuously ,connected to the respective conductors and 21 of a suitable supply circuit of electric energy.

The motor 23 drives a circular disc 2B as by a worm 3|, the disc 28 being mounted on a shaft 33 which shaft is to be considered as being suitably supported in bearings not shown in the drawing. I provide further a cam disc on the shaft 33, the outer radius -of the major portion of this disc being of one dimension and the radius of a portion 31 being of slightly larger dimension and having a peripheral extent in accordance with the length of orf-peak period, as desired by the central station or utility to which the system embodying my invention is to be connected. It is to be understood that shaft 33, and the parts mounted thereon will be turned through one complete revolution in twenty-four hours and I have illustrated the peripheral extent of the portion 31 as being substantially one-third of the total periphery of the disc 35 so that the off-peak period is to be considered as extending over substantially eight hours. At the same time I may, for illustrative purposes, mention that the position of the disc 35 shown in Fig. 1 of the drawing is that which it might occupy at 10 p. m. so that the duration of an oft-peak period of eight hours would be from 10 p. m. to 6 a. m.

While I have illustrated a specific form of tim ing device which may include, although not t shown, a timer dial indicating the time of day, I

.l may use any other form of construction of similar elements effective for the same purpose, namely, so far as has already been described, to cause closure of a control switch at the start of an off-peak period and to cause opening of said switch at the end of an oli-peak period. While not shown it is to be understood that disc 35 may be adjustably mounted on its support, '1n this case the shaft 33, so that the beginning and the end of an off-peak period may be made other than that hereinbefore mentioned.

I provide a control switch designated by the numeral 39, to be controlled or actuated by the timing device and which includes a substantially rigid contact arm 4l and a resilient contact arm 43 which latter is adapted to be operatively engaged by the portion 31 of the disc 35 to cause engagement of the arm 43 with the arm 4I at the start of an off-peak period, to remain in engagement therewith during the entire off-peak period and then to be permitted to move out of engage-- ment with contact arm 4| by reason of the bias inherent in contact arm 43 tending to cause such disengagement after the end of an orf-peak period.

I provide further a third cam disc 45 on shaft I38 which may also be adjustably mounted thereon and which includes a lug 41 extending radially outwardly beyond the rest of the periphery of substantially uniform radius. I provide also an adjustably mounted arm 49 movable on the shaft -but ixed in any desired position by means not shown in the drawing. l

The arm 49 carries a second control switch 5| which includes a relatively rigid contact arm 53 and a resilient contact arm 55 4normally biased out of engagement with arm 53 by its own construction, but moved into engagement with arm 53 by the ear or lug 41 when this lug operatively engages arm 55. I may provide stop pins 51 and 59 in order to limit the peripheral turning movement of manually adjustable arm 49 to certain speciiied lengths of time relatively to the other parts of the timing device.

The tank is provided with an electric heating element 6| which may be of any suitable or desired kind and is here shown generally only as includng a resistor conductor suitably supported in an annular tunnel 63. I do not desire to be limited to this construction since any kind of electric resistor element may be employed by me.

I provide a single electromagnetic contactar 85 which includes an energizing coil 61, a pair of xed contact members 69 and a movable contact bridging member 1|, all of a kind well known in the art. The supply circuit conductor 25 is connected by a conductor 13 with one of the fixed contacts 69 while the other xed contact member 69 is connected by a conductor 15 with one end of heating element 6|, the other endv of which is connected by a conductor 11 with supply circuit conductor 21. When the contact bridging member 1| is in the position shown in the full lines in Fig. 1 of the drawing, the heatwill be traversed by an electric current causing heating of the water in the ing element 6 I tank.

Means for causing energization of the coil 61 of the electromagnetic contactar 65 includes, in addition to the switch 39, an auxiliary or upper thermally actuable switch 19 which includes atubular member 8| properly connected to the wall of the tank to be located within the tank and to be surrounded by the water in the tank. An expansion rod 83, shown schematically only, is supported by the tubular member 8| and is adapted to cause movement of a resilient contact arm I85 whichv is adapted to engage with and be disengaged from a relatively rigid contact arm 81. In the position shown in Fig. 1 of the drawing, the' tubular member 8| is surrounded by relativelyvcold water so that the expansion rod 831s contracted with the result that contact arm .'85 is in engagement with contact arm 81. I desire it to be understood' that the showing of this thermally actuable switch subject to the temperature of the Water in an intermediate portion of the tank is schematic and illustrative only and that any other suitable kind of thermally actuable switch effective for.

the same purpose may be utilized by me and also that this auxiliary thermal switch may be positioned higher up or lower down in' the tank than where shown. A

Supply circuit 'conductor 25 is connected by a conductor 89 with contact arm 43 while contact arm 4| is connected by a conductor 9| with contact arm 85. Contact arm 81 is connected by a conductor 93 with one terminal of coil 61, the

other terminal of which is connected through a conductor 95 with conductor 11.

Let is be assumed that the timing device has caused movement of the parts operated thereby to the. positions shown in Fig. 1 of the drawing and particularly has just caused closure of switch 39. Let it be assumed also that the amount of hot water in the tank is a relatively small quantity so that its lower level is above tubular member 8| whereby tubular member 8| is surrounded by relatively cold. water with the result that contact arms 85 and 81 are in engage- `ment as shown inFig. 1 of the drawing. An

' member 1| will be moved from its lowered .position, shown by the broken lines in Fig. 1 of the drawing, to its upper or closed position shown by the full lines whereby an energizing circuitthrough heating element 6| is closed substantially as follows: From supply circuit conductor 25 through conductor 13 through the contact members 69 and the bridging member 1l, conductor 15, heating element 6| and conductor 11 to the other supply circuit conductor 21.

vThis means that energization of the heating element 6| will be started at the `start of an oi-peak period provided that the amount of hot water in the tank is less than a predetermined minimum, the amount of such cold water being the proportional amount in accordance with the position of the auxiliary thermally actuable switch 19 relatively to the height of the tank. It is within the province of my' invention to place the auxiliary thermally actuable switch in either the position shown in Fig. 1 of the drawing or higher or lower in the tank and this, of course, Will have an eect upon the relative quantity of hot water in the tank and its action upon the auxiliary switch 19.

If, on the other hand, at the time of the start of an oil-peak period when contact arms 43 and 4| have been amount of hot y its lower level extends well below the thermally actuable switch 19, rod 83 will have beenA expanded as to length and will'have moved contact arm 85 out of engagementwith arm 81 so that the hereinbefore described energizing cir'- cuit through coil 61 cannot be effected through.

switch 39 at the start of the oi-peak period.

It is possible for the operator or user of a water heating system of the kind herein described to ensure start of energzation.of the heating element at any preselected time during the offpeak period at his will, this being done by manual movement of the arm 49 carrying the switch 5|. Let it be assumed that the arm 49 has been moved to the position shown in full lines in Fig. 1 of the drawing and let it be assumed that the position of disc 45 on shaft 33 was such that contact arm 55 was moved into engagement with arm 53 at the start this case an energizing circuit will be closed through coil 61 as follows: From supply circuit conductor 25 through conductor 89, contact arms 43 and 4|, conductor 91, contact arms 55 and 53, conductor moved into engagement, the water in the tank is such that y of an off-peak period. In`

99 to one terminal of coil 61 through the coil and then through conductors 95 and 11 to the other supply circuit conductor 21. It is thus evident that an energizing circuit through coil 51 of contactor 55 will be closed at the start of an o-peak period irrespective of the condition of the thermally actuable switch 19, that is, irrespective of whether contact arms 85 and 81 are in engagement with each other or not.

A holding circuit for the contactor coil 61 is as follows: From conductor 25 through conductor 89, contact arms 43 and 4|, conductor 9|, contact arms 85 and 81, conductor 93, coil 51 and conductors 95 and 11 to the other supply circuit conductor 21. It is evident that this holding circuit is not of major importance to hold the-contactor 55 in circuit closing' position since the latch |03 engaging hook end |0| causes contact bridging member 1| to be heldin engagement with iixed contact members 89, 'so that disengagement of contact arms 85 and 81 because of submersion of tubular member 8| in hot water, and opening of the above described holding circuit would not cause openingmovement of bridging member 1|.

Let it be supposed, however, that the amount of `hot water in the tank at the start o! an offpeak periodwas suillclent to extend below the level of tubular member 8| and that contact arm 85 was out of engagement with contact arm 81 and further that the operator had moved arm 49 in a clockwise direction to'call for a delay of say three hours, which position of arm 49 and of switch 5| is shown by the broken lines in Fig. l. No energizing circuit through coil 01 or through heating element 8| will be closed at the start of an off-peak period and only after the lapse o! an adjustably predetermined time, determined by the will of an operator, will contact arm 55 be moved into engagement with contact arm 53 to cause energization, as hereinbefore de. scribed, of coil 51 with resultant energization of heating element 8|.

I wish to point out here that if thegamount of hot water in the tank at the start ofln off-peak period was such as to have the tubular member 8| surrounded by hot water but withdrawals of hot water during thel hereinbefore described delay period should occur causing the tubular member 8| to be surrounded by cold water, energization o! coil 51 of contactor B5 will immediately occur (with resultant energization of heater 5|) virrespective of the fact that contact arm 55 of switch 5| is still out of engagement with contact arm 53, this being caused by engagement of the contact armsl 85 and 81.

` The contactor 65 includes, in addition to the :parts already described, a hook-shaped upper end suitably secured to the amature core structure usually provided in electric magnetic contactors. A latch member |03 is normally yieldingly biased into engagement with the hookshaped end of member |0| by a compression spring which engages an armature core member |01, the latch |03 being suitably secured thereto to be actuated by the armature core |01, when a coil |09 surrounding the same is ener*- gized, core |01 to be moved in a right-hand di'- rection as seen in Fig. l of the drawing, to cause release movement of latch |03 under predetermined operating conditions to be set forth. I may provide a supporting and stop pin associated with latch |03 which is so shaped that its horizontal movement in either direction will be limited by pin Means to control the energization of coil |09 comprises a main thermally actuable switch ||3 which may be of the same general type and construction as switch l19. I have illustrated a tubular member ||5, a relatively rigid contact arm |1 and a resilient contact arm ||9 normally yieldingly biased out of engagement with arm ||1 but adapted to be moved into engagement therewith by an expansion rod |2| supported within tubular member ||5. l

A conductor |23 connects one terminal of coil |09 to contact arm ||9 while a conductor |25 connects the other terminal of coil |09 to the left-h-and fixed contact member 59 and to conductor 15.

The latch member |03 will, as has already been hereinbefore set forth, be biased to its left- -hand or latching position by reason of the biasing spring |05 and if and when coil 61 of contactor 55 is energized as hereinbefore described, the upper hook-shaped end |0| is adapted to move past` the left-hand end of latch |03 which is beveled for that purpose, so that when coil E1 has been energized and has caused quick upward movement of contact bridging member 1| and the upper hook end |0| into the positions shown in Fig. 1 o1' the drawing, these parts will be held in this position by latch |03.

Let it now be assumed that tubular member ||5` is surrounded by hot water, that is. water which has been heated to a predetermined and preferably adjustable temperature value whereby expansion rod I2 has been expanded sulciently to cause engagement of contact arm ||9 with contact arm ||1, an energizing circuit through coil |09 will be closed extending substantially as follows: From supply circuit conductor 25 through conductor 13,` contact member 58 and contact bridging member 1| through conductor |25, coil |09, conductor |23, through contact arms ||9 and ||1 and through conductor 11, to the other supply circuit conductor 21. This energization of coil |09 will cause quick right-hand movement of core 01, resulting compression of spring |05 and right hand movement of latch |03 with the result that contact bridging `member 1| will drop into its lowered or open circuit .position to cause deenergization of the heater 8 `Should deenergization of the heating element 5| occur during the rest of the olf-peak period after the manually adjustable switch 5| has been closed, as hereinbefore described, and should withdrawal of hot water occur.' thereafter during.

the oiI-peak period, it is evident that reenergization of coil 51 and therefore of heater 5| will occur it 'the withdrawal of hot Water is to such an extent that auxiliary thermally actuable switch 19 is subjected to cold water, all of this being evident from the action thereof, as herein before described.

Fig. 2 of the drawing shows the positions of the various parts of my improved water heating system and of its respective elements when the tank is full of hot water at the end of an oiI- peak period. It is to be noted, however, that i! the tank is not entirely full of hot water at the end of the off-peak period so that thermally actuable switch I3 is in the positionshown in Fig. 1 of the drawing, that energization of heater 5| will continue beyond the end of the oiI-peak period even though contact arm 43 is permitted to move 'out of engagement with contact arm 4| and into the position shown in Fig.V 2 of the drawing. This energization of heater 5| will continue for as long as the lower thermally actuablev switch ||3 is subjected to the temperature into `a positionto hold the temperature. It is evident that this prolonged or continued energization of coil El beyond the end of an off-peak period will continue until all of the water in the tank is hot. When the heater 6| has once been deenergized after the end of an off-peak period, as hereinbefore set forth, reenergization thereof cannot occur until the start of the next off-peak period.

The system embodying my invention thus provides a relatively simple .means including relatively feW parts for ensuring starting of the energization of a tank heater atthe beginning of an oil-peak period if the tank contains more thanv a predetermined amount of cold water at the start of van olf-peak period, that will delay energization of the heater for a selected manually adjustable time in case the tank contains more than a predetermined amount of hot water at the start of an oil-peak period, that will cause energization of the heater during the delay period if more than a predetermined quantity of hot water is withdrawn from the tank during the delay period, that will cause leenergizatlon of the heater at any time during an off-peak period if all of the water in the tank has been heated to a predetermined temperature, that will reenergize the vheater during the rest of an olf- ,2,23 of cold water or of water below a predetermined switch closed and a thermally actuable switch tor causing releasing movement of said latch when substantially all of the water in the tank is hot.

3. An oi-peak water heating system for a hot water tank comprising an electric heater, an electromagnetic switch controlling the energization of said heater, a continuously operative timer, a switch adapted to be held closed by said timer during an o -peak period of predetermined duration, a thermally actuable switch subject to the temperature of the water at a certain point in the tank, electric connections between the timercontrolled switch, the thermally actuable switch and said electromagnetic switch to cause energization of the electric heater at the start of theoi-peak period when the thermally actuable switch is subject to water temperature below a predetermined value, an electromagneticallycontrollable latch normally spring biased into position to hold said electromagnetic switch closed and a second thermally actuable switch subject to water temperature at another point in the tank for causing release movement of the latch when the temperature of the water at said lother point is above a predetermined value and consequent deenergization of the electric heater peak period if withdrawals of hot water occur and that will prolong energization of the heater beyond the oil-peak period in case all of the water in the tank is olf-peak period.

It may also be here not hot at the end of the pointed out that the single heater-controlling electromagnetic contacter is controlledv as. to its closing movement by means controlled solely by time or by the joint` action of means controlled by time and by the temperature of an intermediate part of the 'tank contents and that the opening movement of the contactor is effected by means responsive to the temperature of the water in the lower portion or at the bottom of the tank.

` WhileI have -illustrated and described a Spe` cil-lc embodimentof Awater heating system embodying my invention, it is obvious that modications may be made therein and all modications clearly coming within the scope'of the appended claims shall be considered as being covered thereby.

I claim as my inventionzv l.l An oi-peak water heating system for a water tank comprising an electric heater, a magnetiorcontactor controlling the electric circuit of the heater, means including a time-controlled r switch held in closed position during an oil-peakv period of fixed length to cause energization of the contacter and of the heater, an electromagnetically controlled latch normally yieldingly. biased contacto'r in circuit closing position and thermally controlled means subject to the 'temperature of the water in the tank to cause releasemovement of the latch to cause deenergization of the electric heater when substantially all of the water in the tank is hot.

2 An off-peak water heating system for a hot water tank comprising an electric heater, an electromagneticswitch controlling said electric heater, a continuously operative timer, switching means severally controlled bythe timer and' by the temperature` of the water in a certain part of the tank to cause closure of said electromagnetic switch at a predetermined time, anelectromagnetically controlled latch normally yieldingly biased into position to hold said electromagnetic momentarily by said-timer irrespective of the trolled switch. I

4. An off-peak water heating system for a hot water tank comprisingan electric heater, an electromagnetic switch controlling the energization of said heater, a continuously operative timer, a switch adapted to be held closed by said timer during an off-peak period of predetermined duration, a thermally actuable switch subject `to the temperature of the Water ata certain point in the tank, electric connections between the timercontrolled switch, the thermally actuable switch and said electromagnetic switch to prevent energization of the electric heater at the start of the cti-peak period in case said thermally actuable switch is subject to water temperature above a predetermined value, a manually adjustable second timer-controlled switch adapted to be closed at a vselected time after start of an otr-peak period and closing of said iirst timer-controlled switch, said two timercontrolled switches being jointly effective to cause closing of said electromagnetic switch and energization of said heater, spring biased into position to hold said electromagnetic switch in closed position, electromagnetic means on said latch to cause release movement of said latch and a second thermally actuable switch subject to water temperature at another part of the tank for causing energization position of said timer-conof the electromagnetic latch release means, opening of the electromagnetic switch and deenergizaton of the electric heater irrespective of the position of saidrst named timer-controlled switch. y

5. An olf-peak water heating system for ahot water tank comprising an electric heater, an

electromagnetic switch controlling the electric a given value and energization and closure of and energization ot' the electromagnetic switch a latch normally of timer-controlled switches.

' said latch, opening of said electromagnetic switch and deenergization of said heater when said second thermally actuable switch is responsive to a water temperature above a' predetermined value.

6. An ofi-peak water heating system for a hot water tank comprising an electric heater, an electromagnetic switch for said heater and means including a plurality of time and temperature controlled switches for controlling the energization and deenergization of said electromagnetic switch to selectively cause energization of the heater at the start of an off-peak period in case of'the presence of more than a predetermined quantity of cold water in the tank at the start of an off-peak period, to cause continuance of the energization of the heater beyond the 'end of an o-peak lperiod in case of the presence of more than a predetermined quantity of cold water in the tank at the end of an off-peak period and to cause deenergization of the heater when the tank is-full of hot water.

7. An oil-peak water heating system for a hot water tank comprising an electric heater, an electromagnetic switch for said heater and means including a plurality of time and temperature controlled switches for controlling the energization and deenergization of said electromagnetic switch to preclude energization of the heater for an adjustably predetermined length of delay time after the start of an oi-peak period in case of the presence in the tank of less than a predetermined amount o! cold water at said time, to cause energization of the heater during said delay time in case Withdrawal of hot water from the tank causes the tank to contain more than said predetermined amount of cold water, to cause continuance of the energization of said heater after the end of the off-peak period in case of the presence in the tank of more than said predetermined amount of cold water at the end of said off-peak period and to cause deenergization of said heater when substantially all of the water in the tank is hot.

8. An off-peak water heating system for a hot water tank comprising an electric heater, an electromagnetic switch for said heater and means including a plurality of time and temperature controlled switches for controlling the energization and deenergization of said electromagnetic switch to selectively cause energization of the heater at the start of an off-peak period in case of the presence of more than a predetermined quantity of cold water in the tank at the start of an oil-peak period, to 'preclude energization of the heater for an adjustably predetermined length of delay time after the start of an oipeak period in case of the presence in the tank of less than a predetermined amount of coldA water at said time, to causeenergization of the heater during said delay time in case withdrawal of hot Water from the tank causes the tank to contain more than said predetermined amount of cold water, to cause continuance of the energization of said heater after the end of the oipeak period in case of the presence in the tank of more than said predetermined amount of cold water at the end of said oi-peak period and to cause deenergization of vsaid heater when substantially all of the water in the tank is hot. HERMAN M. BIEBEL. 

